Natrona County, WY Roof Snow Load - 15 psf
Natrona County, WY roof snow load, translated
A typical heated home in Natrona County is designed to carry 15 pounds per square foot of snow on its roof, per ASCE 7-22. §7.3.4's low-slope minimum of 15 psf is what actually governs on a flat or low-pitch roof here - higher than the 10.5 psf the base ground-load formula gives.
On a roof that means 33 in. of fresh snow, 12 in. once it packs down, or 3 in. of solid ice - three very different piles for the same load. Modern-code homes carry a load like this without issue; an older addition, a carport, or any flat-roofed section is where it is worth checking first.
Natrona County in numbers
- Design roof snow load15 psf
- Ground snow load, ASCE 7 map15 psf
- National rank#1,352 of 2,758
- Wyoming rank#10 of 18
- Population80,410
- Annual snowfall, NOAA normal71.8 in.
- FIPS56025
Where Natrona County ranks
#10 of 18 Wyoming counties by design load, top 49% of 2,758 nationally - that's Natrona County's spot. 17.5 psf is Wyoming's typical county figure - Natrona County comes in 2.5 psf under it.
FIPS 56025, population 80,410, centered near 42.9776°N 106.7682°W. ASCE 7's underlying ground snow load here is 15 psf before the code's exposure and importance factors bring it to the 15 psf design figure above.
Natrona County: average annual snowfall
Natrona County sees about 71.8 in. of snow most winters, per the CASPER NATRONA CO AP, WY US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use Natrona County's figure
The figure above assumes the case ASCE 7-22 treats as typical: a heated, ordinary-occupancy home on a partially exposed site. Change any of those - exposure, heating, roof pitch, occupancy category - and the real design number moves.
A building permit needs the number at your exact address, not the county average - the free ASCE 7 Hazard Tool returns that from your coordinates in about a minute and produces a PDF a plan reviewer will accept. See the methodology guide.